feat(build): Upgrade to AGP 9.0 and refactor build logic

[jamesarich]

This commit upgrades the Android Gradle Plugin to v9.0.0-beta02 and refactors the build logic to improve modularity, maintainability, and compatibility with the new plugin version.

Key changes include:

• AGP 9.0.0-beta02 Upgrade:

  • Updated the Android Gradle Plugin from 8.13.1 to 9.0.0-beta02.
  • Replaced deprecated android extension access with the androidComponents API for variant configuration in app/build.gradle.kts.
  • Removed obsolete com.android.library and org.jetbrains.kotlin.android plugin aliases, centralizing plugin management in convention plugins.
  • Set android.newDsl=false in gradle.properties to maintain compatibility with existing build scripts during the transition.
    • Hilt is our big blocker here.

• Build Logic Refactoring:

  • Centralized SDK and Java version configurations into config.properties, accessed via a new configProperties extension in ProjectExtensions.kt.
  • Updated KotlinAndroid.kt and KmpLibraryConventionPlugin.kt to read compileSdk, minSdk, and targetSdk from the centralized properties.
  • Removed redundant plugin applications (e.g., com.android.library, org.jetbrains.kotlin.android) from individual convention plugins (AndroidLibraryConventionPlugin, AndroidApplicationConventionPlugin, etc.), as they are now handled by base plugins.
  • Simplified AndroidCompose.kt by removing dependency declarations now handled by the compose-compiler plugin.

• Domain Layer and UseCase:

  • Introduced a new core:domain module to encapsulate business logic.
  • Created SavePacketLogsUseCase to abstract the logic for exporting packet logs to a CSV file, moving this responsibility out of SettingsViewModel.
  • SettingsViewModel now calls SavePacketLogsUseCase for data export, simplifying its implementation.

• Testing Improvements:

  • Added testFixtures to the core:model module.
  • Created NodeInfoFixtures.kt to provide reusable NodeInfo objects for tests.
  • Refactored NodeInfoTest.kt to use the new fixtures.